function x = f_gauss (A, b)
  Ur=horzcat(A,b);
  N=length(b);
  for k=1:(N-1)
     if (A(k,k) == 0)
        error  ("Blad");
     endif
      for j= (k+1) : (N+1)
       for i=(k+1): N
        Ur(i,j) = Ur(i,j) - ((Ur(i,k))/(Ur(k,k))) * Ur(k,j);
        endfor
      endfor
  endfor

      x= [0 0 0];
      for i= N:-1:1
       S=0;
      for j=i+1 : N
     S = S+Ur(i,j)*x(j);
    endfor

    x(i)=((Ur(i,N+1)-S)/Ur(i,i));
  endfor


endfunction